The change of ultrasound velocity in aqueous solution was investigated as a function of particle size and suspension density. NaCl, KNO3, K2SO4 and MgSO(4)(*)7H(2)O was used as model substances. Measurements were made on a series of suspensions with different solid concentration (from 0-60%wt) and particle sizes ranges (from 250-500 mum). It was found that there is a strong relation between the particle size and/or suspension density and the ultrasonic velocity. This relation was correlated with a second degree polynomial equation and the error percent was determined. Also the compressibility of the media and particles were calculated based on Urick equation.